The present invention relates to the field of motor vehicle safety. More specifically, the invention relates to a hybrid gas-generator containing a solid pyrotechnic charge and a reserve of pressurized gas and intended to inflate a cushion for protecting the occupants of a motor vehicle.
Hybrid generators which rely on the principle of producing active gases by mixing gases that result from the combustion of a solid or liquid fuel with distinct cold gases are highly sought-after in motor vehicle safety because they produce gases which are not as hot and which can meet the low-toxicity standards required in motor vehicle safety more readily than can the gases supplied by traditional solid-charge generators.
Various types of hybrid generator have been proposed to those skilled in the art. Patent U.S. Pat. No. 3,813,007 or its counterparts FR-A-2,116,947 and FR-A-2,116,949 have proposed a type of hybrid generator comprising a double base solid powder charge, the combustion gases of which are diluted with a vaporizable liquid contained in a reservoir equipped with a piston that can move under the action of the pressure in the generator.
The relatively complicated structure of this generator and the use of a liquid mean that the person skilled in the art has not adopted this solution.
Patent U.S. Pat. No. 5,199,740 has proposed a gas generator in which the gases from the combustion of a solid pyrotechnic charge are diluted in a space full of pressurized inert gas. Such a generator is also of a very complicated structure.
Application EP-A-0,685,369 has proposed a hybrid generator in which an oxidizing gas mixture under pressure is heated by combustion with a liquid fuel before being diluted in a space containing pressurized inert gas. Such a generator, which requires a number of pressurized chambers, exhibits the same type of drawbacks.